Pipe coupling



Allg 20 1940- H. KRExDEI. 2,211,856

I PIPE counme Filed Feb. 2o, 19:57

l mm

Patented Aug. 2o, l1940 UNITED STATES Pa'rlalvr OFFICE PIPE ooUPmNG HansKreidel, Wiesbaden, Germany, assigner to Patex Societe Anonyme, Basel.,Switzerland,l a corporation of Switzerland Application February 20,1937, `Serial No. 126,751 In Germany July 27, 1936 zclaims. (c1.2x5-'122) ing ring which was contracted about the pipe,

or tube while being moved longitudinally with respect thereto, andcausing the inner edge to cut into the outer wall of the pipe or tube.and form an vannular ridge-like shoulderA against l5 which the ring washeld to grip the pipe and -form a seal which would be tight under highfluid pressure, even when subjected to vibration and other mechanicalstrains.

When using the coupling disclosed in the aforesaid application withextremely thin walled tubing vor with pipe or tubing made of very softmetals, it is desirable to increase the mechanical grip of the sealingring upon the tube Without cutting deeply into the tube, andwithoutcontracting the tube or otherwise aitering the smooth cylindricalsurface of the bore of the tube.

The object ofthe present invention is to provide an improved 4form ofcoupling of the above described type, which may be effectively used invmaking joints in, or connections with tubing having very thin walls orwithA tubing made of u very soft metals.

Other objects will appear from the following description, referencebeing had-to the accompanying drawing, in which:

' Fig. 1 is a longitudinal sectional view of the coupling parts, thetube and sealing ring being shown in quarter-section, the parts being 4oshown in position ready for assembly.

Fig. 2 is a longitudinal quarter-sectional view showing the parts at anintermediate stage of assembly, and also illustrating the sealing ringin the form in which itmay be manufactured.

Fig. 3 is a longitudinal quarter-sectional view showing the completedcoupling joint.

According to my present invention, the sealing ring or sleeve is soconstructed that as the coupling connection is made, two or more cuttingedges at or near the leading end of the ring or sleeve will cut into thewall of the tubing to form va double grip and seal.

The coupling is illustrated as comprising a coupling body I0, which maybe a part of a ma- Nt chineorapparatus, or may be the body of a union.or other pipe fitting. The body is provided With a fluid-conducting boreI2 which terminates at a shoulder I4 in a shortcounterbore I6, and. hasa frusto-conically flaring mouth I8 leading to the counterbore. 5 Thebody has external threads 20, to receive an internally threaded cap nut22 which may be hexagonal or of other non-circular shape. The nut has aninternal frusto-conical or flared surface 24. The tube or pipe 26 to becoupled to lo the body I0 is of substantially the same internal bore asthe body I0 and is inserted in the counterbore I6 with its end inabutment with the shoulder I4'.

A sealing or packing ring or sleeve 28 surrounds u the tube 26 and islocated between the body I0 and nut 22. Ordinarily,'this sealing sleevewill be made of substantially the same'kind of metal as the tube 26 withwhich it is to be used. It is, however, preferably made of slightlyharder 20 material or may have parts thereof work-hardg cned as willhereafter appear. For most uses it is desirable to make the sleeve of ametal which is electrolytically inert with respect to the metal of whichthe tube or pipe is composed. Forcop- 25 per or brass tubing, the sleevemay be cfa suitable brass; for aluminum tubing, aluminum orl duralumin;for wrought iron, cast iron andsteel pipe and tubing, a suitable gradeof steel which is slightly harder than the material of the pipe 30 ortube.

.The ring or sleeve 28 has a counterbore or annular recess 30 formed irits forward or leading end, thus forming a relatively thin hollowcylindrical extension 32. The outer edge 34 of 35 this extension isslightly rounded or chamfered so that itV will not cut into thefrusto-conical surface I8 of the body, While the inner annular edge 36of the extension is relatively sharp, to form a cutting edge. The edge38'at the inner 40 end of the counterbore 30 is likewiserelativelysharp. If the sealing sleeve 28 is not made of a metal which is slightlyharder than that of the pipe or tube with which, it is to be used, theedges 36 and 38 are preferably made slightly 45 harder by a suitableWork-hardening process.

The rearward end of the sleeve 28 ha'sa portion 4Il of slightly enlargeddiameter. The outer end of the sleeve 28 has a frusto-conical or beveledo the - the cutting edge 38- has been contracted substantially to thediameter of the tube. The rearward edge 44 of the sealing ring has alsobeen contracted and is in frictional engagement with the tube.

Upon further tightening of the nut 22 upon the bodyV I0, the sleeve 28will be forced further into the flared mouth I3, further contracting theleading end thereof and pressing the cutting edges 38 and 38 into thetube. The edges will be moving longitudinally with respect to the tubeso that they will shear into the surface of the tube at an angle. Thatis, the paths of the cutting edges 36 and 38 will, as the coupling' nutis screwed tight, dene conical surfaces, and thus form annular grooves48, 48 of saw-tooth cross-section in the outer surface of the tube.Substantially all of the metal from the grooves will be displacedforwardly and form ridges 50,

52 ahead the cutting edges, and there will be noI appreciabledeformation of the inner surface of the tube.

As shown in Fig, 3, the joint iscompleted. A double seal is formedbetween the sleeve and tube by the generally radial surfaces at thecutting edges pressing against the corresponding surfaces of the groovesI6, 48 and ridges 53, 52. The

seal between the body I6 and the sleeve is formed by the pressure of theouter'conical surface of sleeve with the tapering surface i8. Therearward edge M of the sleeve is contracted into n rm contact with thetube so as to maintain a tight mechanical frictional grip upon it. Thisgrip upon the tube is suilibiently tight to prevent or minimize thetransmission of shocks to the seal- 1 ing surfaces. Because of the factthat the ends of the sleeves are radiallyI contracted and the sleevelongitudinally compressed, the sleeve acts as spring lock washer betweenthe nut 22 and body I0 to prevent the latter from becoming loose whenthe joint is subjected to vibration.

As previously stated, the sleeve 28 as shown in Fig. 2, may be initiallyformed in the shape shown in Fig. 2, or `more properly 'of the shapeshown in Fig. l, with the exception that the extension 32 will be bentinwardly as indicated in Fig` 2 with its cutting edge 38 of the samediameter as that ofthe cutting edge 38.. When the sleeve is thuspreformed, more nearly tothe shape it is to assume in the completedjoint. less po'wer and effort is required to make the joint since thenut 22 will be capable of being turned freely until just prior to thetime that the leading portion of the sleeve is contracted inwardly tobring-the cutting edges 38, 38 into contact with the external surface ofthe tube.

In both embodiments of the invention,l the sleeve 28 is preferably madeof a metal lwhich is slightly harder than that of the tube. If made ofthe same metal as the tube, it may be case hardened or work hardened insuch man# ner that the cutting edges 38, 38 are sumciently -hard to becapable of shearing the metal of the tube, and yet retain sumcientductility that the sleeve will contract as it is forced into the ilaringmouth i8 of the'body.

The completed joint shown in Fig. 3 may be disconnected an indefinitenumber of times and reassembled without affecting the efficacy of theseal obtained. Of course when'the nut 22 is unscrewed to disconnect thetube 28 from the body I0, the sleeve 28 will remain secured to the tubel due to the fact that the cutting edges 38, 38 are embedded in theannular grooves 46, I8. If the nut is drawn up farther than indicated inFig. 3, the grooves 88, 88 will be cut somewhat deeper than shown inFig. 3 and the ridges 50, 52 will be correspondingly increased in size.

The completed joint is very eiiective in resisting mechanical strains.placed upon the tube. Edge 4 and adjacent portions which are pressedinto contact with the outer surface of the tube form an effective gripto hold the tube against formed with tubing which is slightly out ofround and tubing the external surface of which is irregular due to thepresence of scale or which is not smooth for any other reason.

The coupling may be used with very thin wall pipe and tubing ofsubstantially all the commercial 'sizes and of the various differentmetals and alloys used fortubing, such as copper, brass, wrought iron,lsteel, stainless steel, aluminum, and duralumin. It has been found thatthe coupling of my invention will withstand iiuid pressure in excess ofthat which will be withstood by the tube itself, and that likewise whentested to destruction for its resistance to vibratory and other.mechanical strains, the ruptures and breakage will take place in thetubing external to the coupling rather than within the coupling.'

In the use of my invention, material savings in cost are effected, notAonly by virtue of the fact that the -end of the tube does not need tobe prepared especially to receive the coupling, but also in the factthat the 'tubing used may in many instances be of lesser wall thicknessthan would otherwise be required if the tubing were to be threaded ortofbe connected by means of other types of couplings, thus saving in thecost of the tubing. Where reduction in weight is a factor, as inairplane construction, the coupling of my invention possesses verypronounced advantages overthreaded .connections and other types ofcouplings and joints.- The fact that the tube may be readilydisconnected from the body of the coupling and reconnected thereto alarge number of times, and still maintain a fluid-tight and strongmechanical joint, is very advantageous in many instances where thecoupling is to be. used.

While I have shown only the preferred embodiments of my invention, itwill be apparent to those skilled in the art that various modificationsthereof may be made without departing from the spirit of my invention.For example, if it is desired further to decrease the depth ofthe'grooves cut into the tube by the-cutting edges of the sleeve, thenumber of cutting edges vmay be increased to three or more, in whichcase three ormore grooves will be cut into thetube.

but each groove will be very shallow. Itherefore desire the scope of myinvention to be limited only by the claims which follow.

I claim: l. A pipe coupling comprising a pipe receiving member havingascrewthreaded'projection into which the end of the pipe is received,said adapted to be recelved over the end of a length projection havingan internal inclined wall, a nut fitting over said projection and havinga screwthreaded connection therewith, and a pipe engaging memberprojecting into the 'projection on the pipe receiving member and havinga leading edge which normally engages the pipe, the outer face of saidpipe engaging member engaging the inclined face of the vpipe receivingmember, said pipe engaging member being recessed on its inner face, nearthe said pipe engaging edge and to the rear thereof and opposite theinclined face on the pipe receivingvmem- 20 ber, the inner face of therecessed portion .be-

ing normally separated from the outer face of the pipe by a space,whereby when the nut is tightened the said pipe engaging edge is forcedinwardly and digs into the metal of` the pipe so as -to form a sealingshoulder thereon, and a second edge to the rear of said recess and whichnormally engages thevpipe and which also digs into' the metal of thepipe to form a second sealing shoulder thereon when said nut istightened.

2. A clamping element for use with a coupling having pressure applyingmeansand of metal pipe and pressed into biting engagement therewithcomprising a continuous sleeve having an inner bore provided with aplurality of spaced independent biting edges of substantially equaldiameter slightly greater than the diameter of said pipe, said edgesbeing formed near one en'd of said sleeve and spaced from one vanotherby a recess formed in'said inner bore,

the periphery of said sleeve being provided with conical portionsadjacent its ends adapted to cooperate with said pressure applying meansto force said edges inwardly to dig into the wall of said pipe and formthereon spaced sealing shoulders.

HANS KREIDEI...

